In an electric motor having a wound stator and a permanent magnet rotor, the stator windings, when electrified, generate a rotating magnetic field which causes the rotor to rotate. In a so called IPM (internal permanent magnet) rotor, a plurality of permanent magnets are embedded in a rotor core. The permanent magnets are separate and each form a N pole or S pole of the rotor, wherein the N pole magnets and the S pole magnets are alternately arranged in the circumferential direction of the rotor core. However, this type of rotor has a low magnetic concentration which results in a motor with a low power density.
Therefore, there is a desire for an improved permanent magnet rotor that can overcome the above described shortcomings